Water-based magenta ink composition and method of ink-jet recording

ABSTRACT

The present invention relates to a water-based magenta ink composition which has satisfactory storage stability, has a hue and vividness suitable for ink-jet recording, and gives prints having high fastness to light and water, and a magenta dye suitable therefor. More particularly, the present invention relates to a water-based magenta ink composition characterized by containing a disulfonic acid derivative of a compound represented by Formula (2)                    
     or the salt thereof as the dye component, an ink-jet recording method using said composition, and magenta dye containing little inorganic salt and little mono-sulfonic acid compound and being suitable for the said composition.

TECHNICAL FIELD

The present invention relates to an ink composition, more particularlyto a water-soluble magenta ink composition for ink-jet recording, whichcontains an anthrapyridone disulfonic acid compound or the salt thereofas the colorant having a wide range of blend color and an excellentproperty in color tone, light fastness and water fastness; an ink-jetrecording method using said composition; an water-based magenta dyecomprising said disulfonic acid compound or the salt thereof having alow content of inorganic salt; and a method for producing saiddisulfonic acid compound or the salt thereof having a low content ofsaid inorganic salt.

BACKGROUND ART

Diverse ink jetting processes have been developed for the recordingmethod by ink-jet printer, and each method comprises the process ofgenerating ink droplets and then depositing them onto various recordingmaterials (such as paper, film, cloth). The recording method by means ofink-jet printer has rapidly been spread in recent years and will bepropagated in future because the method makes no noise due to the systemin which a recording head does not contact with the recording materialand because the method advantageously allows the printer easily to bedownsized, to work in a high-speed and to give color printing. In orderto record in color an image information or a character information on acomputer color display by an ink-jet printer, it is generally printed toby subtractive color mixing of four colored-inks, namely yellow,magenta, cyan and black. In order to reproduce an image pictured byadditive color mixing of R, G ,B on a CRT display as identical aspossible by subtractive color mixing, the dyes used therefor, especiallyfor a YMC ink, are desired to have color hues close to the respectivestandards of YMC (“Japan Color Standard Paper” published by JapanPrinting Machinery Manufacturers Association)and vividness.Additionally, it is required that the resulting ink composition isstable for long-term storage and that the resulting printed image is ofa high optical density and has excellent fastness including waterfastness and light fastness. The present invention relates to a magentaink.

The use of ink-jet printers are enlarged from a small-sized one for OAto a big-sized one for industrial use. So, there arise a keen demandmore than ever on fastness such as water fastness and light fastness ofthe printed image. The water fastness is substantially improved bycoating inorganic or organic micro particles such as cationicpolymer(not an inorganic particle), porous silica, alumina sol andspecial ceramics which can absorb dye from ink with PVA resin on a papersheet. Various coated sheets for ink-jet printing are already availableon the market, but they can not always give a satisfactory waterfastness. Light fastness is not yet improved by an establishedtechnique. Especially, the majority of magenta dyes, one of fouroriginal colors of YMCK, are poor in light fastness, and its improvementis an important problem to be solved.

The chemical skeletal structure of magenta dyes used in a water-solubleink for ink-jet recording is represented by a xanthene type disclosed byJP Laid-Open No.89811/1979, JP Laid-Open No.60053/1996 and JP Laid-OpenNo.143798/1996, or an azo type using the H acid disclosed by JPLaid-Open No.62562/1986, JP Laid-Open No.156168/1987, JP Laid-OpenNo.203970/1991, JP Laid-Open No.157698/1995 and JP PublicationNo.78190/1995. The xanthene type is indeed excellent in hue andvividness, but is inferior in light fastness. The azo type using the Hacid is good in hue and water fastness, but is inferior in lightfastness and vividness. As disclosed by JP Laid-Open No.203970/1991, forexample, some magenta dyes excellent in vividness and light fastnesshave been developed from the azo type family, but are still inferior inlight fastness to the other hue of dyes such as yellow dyes and cyandyes represented by copper phthalocyanine type.

For a chemical skeletal structure of magenta dyes excellent in vividnessand light fastness, an anthrapyridone type is known as disclosed by JPLaid-Open No.195775/1982, JP Laid-Open No.74173/1984 and JP Laid-OpenNo.16171/1990, but is not yet able to satisfy all of the properties in awide range of blend color, hue, vividness, light fastness, waterfastness and stability in solution. The U.S. Pat. No. 2,644,821discribes an anthrapyridone type compound including the compound ofbelow Formula (2) and its disulfonic acid compound as a good lightfastness and water fastness of dye, but they are intended to use mainlyfor fiber-dyeing and can not show a high quality suitable for anink-jetting ink, if used directly with no additional procedures.

An object of the present invention is to provide a water-based magentaink composition which has a wide range of blend color in hue andvividness suitable for ink-jet recording and gives the recorded materiala high fastness in light fastness and water fastness; and a magenta dyesuitable therefor.

DISCLOSURE OF THE INVENTION

The present inventors made a diligent study to solve the above problemand, as a result, have completed the present invention. Namely, thepresent invention is as follows:

(1) A water-based magenta ink composition, which comprises thedisulfonic acid derivative of a compound represented by Formula(2) orthe salt thereof as the dye component.

(2) A water-based magenta ink composition according to the above term(1), wherein said disulfonic acid derivative of a compound representedby Formula(2) is 85% or more (area ratio according to high performanceliquid chromatography(HPLC)) in content and a monosulfonic acid compoundof the compound represented by Formula(2) according to the above terms(1) is 10% or less(area ratio according to HPLC)in content.

(3) A water-based magenta ink composition according to the above term(1) or (2), wherein said disulfonic acid compound is a compound (or thesalt thereof, hereinafter likewise) represented by Formula(1).

(4) A water-based magenta ink composition according to any of the aboveterms (1) to (3), wherein said composition contains water and an organicsolvent.

(5) A water-based magenta ink composition according to any of the aboveterms (1) to (4), wherein an inorganic salt in said dye component is 1%or less in content.

(6) A water-based magenta ink composition according to any of the aboveterms (1) to (5), wherein said composition is for ink-jet recording.

(7) A method for ink-jet recording, which comprises using thewater-based magenta ink composition according to any of the above terms(1) to (5) for an ink in the ink-jet recording way that ink droplets arejetted responding to recording signals to record on a recordingmaterial.

(8) A method for ink-jet recording, which comprises using thewater-based magenta ink composition according to any of the above terms(1) to (5) for a magenta ink, and using a water-based cyan inkcontaining a water-soluble metal phthalocyanine dye for a cyan ink inthe ink-jet recording way that ink droplets are jetted responding torecording signals to record on a recording material.

(9) A method for ink-jet recording according to the term (8), whereinsaid recording material is a polyamide fiber material, which isthermally treated after jetting said ink composition.

(10) A method for ink-jet recording according to the term (8), whereinsaid recording material is a sheet for information transmitting.

(11) A method for ink-jet recording according to the term (10), whereinsaid sheet for information transmitting is a surface-treated sheet.

(12) An ink-jet printer, which comprises being equipped with a containerstoring the water-based magenta ink composition according to any of theabove terms (1) to (5) and a container storing the water-based cyan inkcontaining a water-soluble metal phthalocyanine dye.

(13) A dye for water-based magenta ink, which comprises containing thedisulfonic acid compound represented by Formula(1) or the salt thereofby 90% or more(area ratio according to HPLC), the monosulfonated product(monosulfonic acid compound) of the compound represented by Formula(2)by 5% or less(area ratio according to HPLC), and the inorganic salt by1% or less.

(14) A method for producing the disulfonic acid compound represented byFormula (1) or the salt thereof, which comprises disulfonating theanthrapyridone compound represented by Formula (2) with fuming sulfuricacid, salting out conventionally the disulfonic acid compound thusobtained to give a wet cake, and then treating the wet cake with ahydrous lower alcohol.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the range of blend color of the dyes.

DESCRIPTION OF SYMBOLS

In FIG. 1, the axis X represents a*, and the axis Y represents b* on theL* a* b* calorimetric system. Y shows yellow, R shows red, M showsmagenta, B shows blue, C shows cyan and G shows green. The solid lineexpresses the range of blend color of the dyed product in Example 2 andthe dotted line expresses the range of blend color of the dyed productin Comparative Example 1.

BEST MODE FOR CARRYING OUT THE INVENTION

The water-based magenta ink composition of the present invention ischaracterized by containing the disulfonic acid compound of the compoundrepresented by the above Formula(2)or the salt thereof. The disulfonicacid compound of the compound represented by the above Formula(2)is 85%or more, preferably 90% or more, more preferably 92% or more, andspecially preferably 95% or more in content in the dye component by arearatio according to HPLC(hereinafter measured in the condition asdescribed below: Column: Inertsil ODS-2(6.0, I,D, 150 mm), Mobile Phase:CH₃CN/0.05 wt % NH₄H₂PO₄=40/60(w/w), Flow Rate: 0.8 ml/min, Col.Temp.:40° C., Detector: UV-254 nm). An example of the disulfonic acidderivative of the compound represented by the above Formula(2) isrepresented by the above Formula (1).

The dye component used in the present invention, which is obtained bysulfonating the compound represented by the above Formula(2), containsthe monosulfonic acid compound by-produced in the production process inaddition to the disulfonic acid. The content of the monosulfonic acidcompound is desirably as low as possible for the purpose of easy inkproduction (for example, filtration), ink storage stability andvividness of the recorded product, and is 10% or less(including 0%),preferably 5% or less, more preferably 2% or less and speciallypreferably 1% or less. It is of course best that the ink composition ofthe present invention contains no compound of Formula (2).

The dye component used in the present invention can be obtained bysulfonating the compound represented by Formula (2) (the compound ofFormula (2) is described in U.S. Pat. No. 2,644,821) in sulfuric acidcontaining fuming sulfuric acid. The concentration of fuming sulfuricacid in sulfuric acid is preferably 5 to 12% by weight, more preferably6 to 10% by weight. The reaction temperature is generally 0 to 60° C.,preferably 10 to 30° C. Further, the reaction time varies depending onthe reaction temperature, but is generally 5 minutes to 20 hours, andabout 30 minutes to 5 hours in an preferable embodiment. The sulfonationterminates when no compound of the formula (2) is identified and themonosulfonic acid compound decreases in concentration to 10% or less,preferably 5% or less, more preferably 2% or less, especially preferably1% or less in concentration according to the HPLC area ratio. After thecompletion of the reaction, the reaction solution is poured in anice-water, followed by salting out, filtration and drying, to obtain thedye containing the compound of Formula (1) (hereinafter, representingthe dye containing the monosulfonic acid compound and the disulfonicacid compound). The product is desired to be treated with a loweralcohol such as methanol and ethanol upon necessity to make a dye havinga low content of inorganic salt suitable for the ink composition of thepresent invention. It is sufficient for the treatment to conduct adesalting treatment, for example, by a conventional method such asreverse osmotic membrane or by stirring a dry product or a wet cake,preferably a wet cake of the dye component of the present invention inhydrous lower alcohol, preferably in a mixed solvent of methanol andwater, then filtering and drying. Either treatment is possible, however,the latter one is more preferable. The preferable amount of a solvent inthe latter treatment is about 1 to 20 times(by weight), preferably 2 to10 times that of the dry product or the wet cake. There is no limit intreatment time as it varies depending on a treatment amount, an amountof hydrous lower alcohol and the other condition, but it is generallyseveral minutes to several hours, preferably about 10 mins to 3 hrs.There is no limit in treatment temperature, in particular, but isgenerally 10 to 40° C., preferably an ambient temperature. The alcoholcontent in a hydrous lower alcohol is generally 20% to 95% by weight,preferably 50% to 90% by weight, more preferably 70% to 85% by weight.

The dye thus obtained exists as a free acid or the salt thereof. Thealkali metal salt, the alkali earth metal salt, the alkylamine salt, thealkanolamine salt or the ammonium salt may be used in the presentinvention. The preferable salt includes an alkali metal salt such as thesodium salt, the potassium salt and the lithium salt, and analkanolamine salt such as the monoethanolamine salt, the diethanolaminesalt, the triethanolamine salt, the monoisopropanolamine salt, thediisopropanolamine salt and the triisopropanolamine salt.

The dye component thus obtained contains the monosulfonic acid compoundand the inorganic salt in their least amounts and, therefore, issuitable for an ink composition of the present invention. The content ofmonosulfonic acid compound, for example, can be decreased to 10% or less(including 0%), preferably 5% or less, more preferably 2% or less,specially preferably 1% or less relative to the total dye componentaccording to the HPLC area ratio. The content of the inorganic salt canbe decreased to 5% or less, preferably 3% or less, more preferably 1% orless relative to the total dye component. The content of the inorganicsalt can be determined by measuring Cl⁻ and SO₄ ²⁻ according to ionchromatography; heavy metals according to atomic absorptionspectrography or inductively coupled plasma emission spectrography; orCa²⁺ and Mg²⁺ according to ion chromatography, atomic absorptionspectrography or inductively coupled plasma emission spectrography.

The water-based ink composition of the present invention can be obtainedby dissolving the above dye component in water or a hydrous solvent(awater containing organic solvent as will be described later). Thepreferable ink pH is about 6 to 11. The more preferable dye component ofa water-based ink composition, when used in an ink-jet recordingprinter, contains an inorganic material such as the chloride and thesulfate of a metal positive ion in the amount as little as possible. Forexample, the total content of sodium chloride and sodium sulfate in thedye component is 1% by weight or less, preferably 0.5% or less, morepreferably 0.1% or less.

The water-based ink composition of the present invention is prepared byusing water as a medium and contains the dye component preferably by 0.1to 20%, more preferably 1 to 10%, more preferably 2 to 8% by weight. Thewater-based ink composition of the present invention also may contain awater-soluble organic solvent 60% or less, preferably 50% or less, morepreferably 40% or less, the most preferably 30% or less by weight. Thelower limit may be 0% by weight, but is generally 5% or more, morepreferably 10% or more, the most preferably 10 to 30% by weight. Thewater-based ink composition of the present invention may contain inkregulators by 0 to 10%, preferably 5% or less by weight. The remainderexcept the above components is water.

The water-soluble organic solvent includes a C1-C4 alkanol such asmethanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondarybutanol and tertiary butanol; a carboxylic amide such asN,N-dimethylformamide and N,N-dimethylacetoamide; a lactam such asε-caprolactam and N-methylpyrrolidin-2-one; urea; a cyclic urea such as1,3-dimetylimidazolidin-2-one or 1,3-dimethylhexahydropyrimid-2-one; aketone or a keto-alcohol such as acetone, methyl ethyl ketone, and2-methyl-2-hydroxypentan-4-one; an ether such as tetrahydrofuran anddioxane; mono-, oligo- or poly-alkylene glycol or thioglycol havingC2-C6 alkylene units, such as ethylene glycol, 1,2- or 1,3-propyleneglycol, 1,2- or 1,4-butylene glycol, 1,6-hexylene glycol, diethyleneglycol, triethylene glycol, dipropylene glycol, thiodiglycol,polyethylene glycol and polypropylene glycol; polyols (triols) such asglycerin and hexane-1,2,6-triol; C1-C4 alkyl ethers of polyhydricalcohols, such as ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, diethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, triethylene glycol monomethyl ether, and triethyleneglycol monoethyl ether; γ-butyrolactone; and dimethylsulfoxide. Thesesolvents may be used in a combination of two or more. Two or more ofthese are in many cases combined to use.

Among these water-soluble organic solvents, preferable examples areN-methylpyrrolidin-2-one and mono-, di- or tri-alkylene glycol havingC2-C6 alkylene units(mono-, di- or triethylene glycol, dipropyleneglycol), glycerine, and dimethylsulfoxide. At least one or a combinationof two or more selected from the above mentioned groups consisting ofthem is preferably used. At least one selected from the group consistingof N-methylpyrrolidin-2-one, glycerine, ethylene glycol, diethyleneglycol and dimethylsulfoxide is especially preferably used.

The ink regulators, which are all the components except water, a dyecomponent and a water-soluble organic solvent, include a preservative, apH adjusting agent, a chelating agent, a rust preventive, awater-soluble ultraviolet absorbing agent, a water-soluble polymericcompound, a dye dissolving agent, and a surfactant. The preservativeincludes sodium dehydroacetate, sodium sorbate, sodium2-pyridinethiol-1-oxide, sodium benzoate and sodium pentachlorophenol.The pH adjusting agent includes any substance that can control the inkpH within a range of 6 to 11 with no adverse effect on the inkpreparation. The examples are alkanolamines such as diethanolamine andtriethanolamine; alkali metal hydroxides such as lithium hydroxide,sodium hydroxide, and potassium hydroxide; ammonium hydroxide; or alkalimetal carbonates such as lithium carbonate, sodium carbonate andpotassium carbonate. The chelating reagent includes sodiumethylenediaminetetraacetate, sodium nitrilotriacetate, sodiumhydroxylethylenediaminetriacetate, sodium diethylenetriaminepentaaceate,and sodium uramil diacetate. The rust preventive includes acidichyposulfite salts, sodium thiosulfate, ammonium thioglycolate,diisopropylammonium nitrite, tetranitrate pentaerythritol, anddicyclohexylammonium nitrite.

The ink composition of the present invention is prepared by adding theabove dye and the above water-soluble organic solvent and the inkregulators upon necessity to water such as distilled water with noimpurities contained therein and mixing them together. Alternatively,the dye may be added to dissolve in a mixture of water, the abovewater-soluble organic solvent and the ink regulators. The resulting inkcomposition may be filtered, if necessary, to remove the contaminantsfrom the composition.

A recording material used in ink-jet recording includes an informationtransmittance sheet such as paper and film, fiber and leather.

It is preferable that the information transmittance sheet issurface-treated and, practically, is set with an ink-acceptable layer onthe base material. The ink-acceptable layer can be set, for example, byimpregnating or coating a cationic polymer on the above basementmaterial; or by coating an inorganic fine-grain which can absorb the dyefrom an ink such as porous silica, alumina sol and special cebamictogether with a hydrophilic polymer such as polyvinyl alcohol andpolyvinyl pyrrolidone on the above base material. The sheet set withsuch an ink-acceptable layer is generally called an ink-jet specialpaper (film)or a glossy paper (film), and is available on the market,for example, as Pictorico(by Asahi Glass KK), Color BJ Paper, Color BJPhotofilm sheet(by Canon KK), Color Image Jet special paper(by SharpKK), Superfine special glossy film(by Seiko Epson KK)and Pictafine(byHitachi Maxell KK). A plain paper can be of course used for a recordingmaterial.

The preferable fiber is a polyamide fiber such as nylon, silk and wool,and is of nonwoven fabric or cloth. The fiber can be dyed by adhering anink composition of the present invention to said fiber preferably byink-jet recording, and then fixing by wet heating(for example, at about80 to 120° C.) or dry heating(for example, at about 150 to 180° C.) togive the dyed product which is excellent in vividness, light fastnessand washing fastness.

A method for ink-jet recording of the present invention can be carriedout, for example, by setting an ink-jet printer with the containercontaining the above water-base magenta ink composition, and thenrecording conventionally on a recording material. The ink-jet printerincludes a piezo type printer utilizing the mechanical vibration and abubble-jet type printer using bubbles generated by heating.

In the method for ink-jet recording of the present invention, the abovewater-based magenta ink composition is used together with a yellow inkcomposition, a cyan ink composition, and a black ink composition uponnecessity. The water-based cyan ink composition, if it contains asoluble metal phthalocyanine dye, is preferably used together with theabove water-based magenta ink composition to give a good result that thecolor tone changes hardly in a light fastness test after color-mixing.Metals in the water-soluble metal phthalocyanine dye includes copper,nickel and aluminium, and copper is preferable. The water-soluble copperphthalocyanine dye includes C.I.direct blue86, C.I.direct blue87,C.I.direct blue199, C.I.acid blue249, C.I.reactive blue7, C.I.reactiveblue15, C.I.reactive blue21 and C.I.reactive blue71.

The water-based cyan ink composition containing the water-soluble metalphthalocyanine dye is produced, for example, by a method similar to thatof the above water-based magenta ink composition and injected in acontainer, which is set at the prescribed position of an ink-jet printerto use in the same way as the container of the above water-based magentaink composition.

The water-based ink composition of the present invention can give anideal magenta color which has vividness, color tone indicated in theabove “Japan Color Standard Paper”, high tinge and moderate blueness,and therefore, can be used together with a yellow or cyan ink to give awide visible range of color tone. Further, the composition can be usedtogether with existing yellow, cyan and black excellent in lightfastness and water fastness to give a recorded product excellent inlight fastness and water fastness.

EXAMPLE

The present invention will be described below in more details withreference to Synthesis Example and Example. “part” and “%” in thedescription are shown by weight unless otherwise specified.

Synthesis Example 1

63.7 parts of 96% sulfuric acid was charged in a reactor, followed byaddition of 65.9 parts of 32.7% fuming sulfuric acid thereto undercooling on ice, to prepare 7.9% fuming sulfuric acid. 20.4 parts of theCompound of Formula(2) was added thereto below 20° C. under cooling onice, sulfonated at a temperature of 20 to 25° C. for 3 hours, and thenadded to 300 parts of icy water, followed by addition of 20 parts ofsodium chloride under stirring. The solution was stirred for 1 hr,filtered and then washed with 30 parts of 10% aqueous sodium chloridesolution to obtain a wet cake. The wet cake was stirred with 300 partsof water for 30 min, and filtered to remove a small amount of insolublematter. To the filtrate 25 parts of sodium chloride was added understirring for salting out, followed by stirring for 1 hr. The resultantproduct was filtered and dried to obtain a reddish powder of the dyecomponent to be used in the present invention.

Alternatively, the wet cake was stirred at the room temperature for 1 hrin methanol 2.3 times as much as the wet cake by weight, filtered,washed with methanol and dried to obtain 24.3 parts of a clearly redcrystal of the dye (λmax: 529 nm(in water)) containing the compound ofFormula (1) and having the least amount of inorganic salt.

The product contained the disulfonic acid compound represented byFormula (1) by 95% or more, monosulfonic acid compound by 1% or less anda total of sodium chloride and sodium sulfate by 1% or less according tothe HPLC area ratio.

Example 1

(1) Preparation of the Ink Composition

The water-base ink composition for ink-jet printing was produced bypreparing a liquid of the composition as described in Table 1 below andfiltering through a 0.45 μm membrane filter (by Toyo Roshi KK). Thecomposition deposited no crystal even after 6 months of the productionand so had good storage stability.

TABLE 1 (Composition) Dye containing the compound of Formula(1)(note)4.5 parts Water 75.5 parts  N-methylpyrrolidine-2-one 5.0 parts Ethyleneglycol 5.0 parts Glycerin 5.0 parts Urea 5.0 parts Total 100.0 parts 

(note) the monosulfonic acid compound content of 0.5% or less(measuredby HPLC in the above condition); the total content of sodium chlorideand sodium sulfate of 1% by weight or less; solubility in pure water(ionexchanged water)of about 100 g/L (25° C.)

(2) Ink-jet Recording

By using an inkjet-printer (Trade name: NOVAJET III, by ENCAD CO.),ink-jet recording was done on an available coated sheet (CoatedpaperSTX73A4 for color image jet; by Sharp, Co.).

(3) Hue and Vividness of Recorded Image

A recorded paper was applied to COMSEK-V colorimetric system (by NipponKayaku KK) to calculate L* ,a*,b* values. Hue was evaluated bycomparison with color samples of standard magenta of the “Japan ColorStandard Paper” published by Japan Printing Machinery ManufacturersAssociation (JNC), and vividness was evaluated by the formula:

C*=((a*)²+(b*)²)^(1/2)

(4) Light Fastness Test of Recorded Image

A carbon arc fade meter (by Suga Testing Machine Co.) was used toirradiate carbon arc on the recorded papers for 20 hours. Change betweenbefore and after the irradiation treatment was determined according toJIS blue scale, and color difference between before and after theirradiation treatment was measured by the above colorimetric system.

(5) Water Fastness Test of Recorded Image

A recorded paper was immersed in a beaker of water, stirred for 2minutes, picked out, and air-dried. Change between before and after theimmersion treatment was determined according to JIS brown gray scale,and color difference between before and after the immersion treatmentwas measured by the above calorimetric system.

Test results in hue, vividness, light fastness, and water fastness ofrecorded images printed by the water-based magenta ink compositionprepared in Example 1 are shown in Table 2.

TABLE 2 Light Water Vivid- fastness fastness Hue ness Judgment JudgmentL* a* b* C* (ΔE) (ΔE) JNC 46.3 74.4 −4.4 74.5 Standard Magenta Ink 47.773.1 −11.4 74.0 Grade 4 Grade 4 composition (8.3) (10.2) of Example 1

Table 2 reveals that the ink composition of Example 1 is excellentbecause the magenta is close to the standard magenta in hue andvividness and the differences in color is little between before andafter the respective test of light fastness and water fastness. Further,the dye component used in the Example, which has a solubility in waterof 100 g/L, is excellent for ink-jet recording and can produce a highconcentration of ink composition.

Example 2

(1) Preparation of Ink Composition

A magenta ink composition was produced by the same way as described inExample 1 except that 3.8 parts of the dye containing the compound ofFormula (1) and 76.2 parts of water were used. For Comparative Example1, a magenta ink composition was produced by using thedye(M-2:C.I.(Color Index) Acid Red 82)as described in JP Laid OpenNo.195775/1982 and adjusting its optical density to be equal to theabove ink composition.

(2) Ink-jet Printing

In order to determine the range of blend color, the above (1) inkcomposition for a magenta ink composition, the yellow ink and the cyanink attached to a printer were used to print in unicolor and blendcolor(red, blue), where the ink-jet printer(Trade name: BJF-600, byCanon KK) and the available coated sheet(Coated paper STX73A4 for colorimage jet; by Sharp, Co.) were used.

(3) Determination of Color

a*, b*, and C* were calculated according to the way as described inExample 1(3). The results are shown in Table 3 and FIG. 1.

TABLE 3 red magenta blue yellow cyan green a* Exam. 2 69.6 74.1 19.5−1.4 −28.9 −47.8 Comp. 1 63.8 71.1 11.2 b* Exam. 2 44.3 −5.6 −52.5 78.6−38.9 38.6 Comp. 1 52.9 11.3 −48.6 C* Exam. 2 74.3 Comp. 1 72.0 Exam. 2Example 2; Comp. 1 Comparative Example 1

Table 3 reveals that the magenta used in the present invention is −5.6in b* which is shifted by 16.9 toward the minus direction from that ofthe magenta of Comparative Example 1, so that the former is an idealmagenta color having a moderate blueness. The blue obtained by mixingthe cyan also is −52.5 in b*,so that it has a more strong blueness. Itis found by plotting a* and b* values of Table 3 on a chromaticitydiagram that the magenta of the present invention has a wider range thanthat of Comparative Example 1 in the field of +a* and −b*, which meanssaid magenta can exert more hue by a blend color in this field.Furthermore, the magenta used in the present invention has a highervalue of C*, the indicator of vividness, which means it has a highervividness. These results show that a higher vividness, a wider range ofblend color and, particularly, a more excellent B(blue) and M(magenta)can be obtained when the ink composition of Example 2 is used. The sametests of light fastness and water fastness conducted on the sample ofComparative Example 1 as on the sample of Example 1 reveal that it is ofgrade 4 in light fastness but is grade 3 in water fastness so that it isinferior in water fastness to the magenta used in the present invention.

Example 3

(1) Preparation of Ink Composition

A magenta ink composition was produced by preparing and filtering in thesame way as described in Example 1 except the case in which the magentadyes as described below were used.

Magenta Dye

M1: the magenta dye used in the present invention

M2: the available ink (containing an azo type dye) for as ink-jetprinter

Cyan Dye

C1: C.I.direct blue 86(cupric phthalocyanine type dye)

C2: C.I.direct blue 199(cupric phthalocyanine type dye)

C3: C.I.reactive blue 71(cupric phthalocyanine type dye)

(2) Ink-jet Printing

The ink-jet record was conducted according to Example 1 by using theink-jet printer (Trade name: NOVAJET III, by ENCAD CO.)with a magentaink alone or with a magenta ink and a cyan ink overlapped to anavailable plain paper (PB PAPER, by Canon KK) and the glossy paper(ColorBJ photo sheet film(CA-101)by Canon KK)having the dye-acceptable layeron them.

(3) Light Fastness Test of Recorded Image

The recording paper printed in (2) was subject to a 48 hrs lightfastness test using the acceleration type xenon light fastness testermade by WACOM.

(4) Determination of Color

Hues of the recorded image before and after the light exposure weremeasured to calculate the olor difference(ΔE)using thecolorimeter(GRETAG SPM59, by GRETAG Co.). The results are shown in Table4.

TABLE 4 No. General paper Enameled paper Remark 1-1 11.3 9.6 M1 alone1-2 6.1 7 M1 and C1 overlapped 1-3 3.0 5.8 M1 and C2 overlapped 1-4 6.66.9 M1 and C3 overlapped 2-1 11.1 13.5 M2 alone 2-2 12.6 17.8 M2 and C1overlapped 2-3 11.3 15.3 M1 and C2 overlapped 2-4 10.2 23.5 M1 and C3overlapped

In Table 4, No.1-1 to No.1-4 are the present invention samples andNo.2-1 to No.2-4 are the reference samples. In Comparison of No.1-1 withNo.2 -1 shows they are of the same level in color difference(ΔE)betweenbefore and after the exposure on the plain paper. However, the referencesample shows a larger color difference due to the exposure on the glossypaper than on the plain paper; contrary to the above, the presentinvention sample shows a smaller color difference on the glossy paperthan on the plain paper. These facts mean that both the presentinvention sample and the reference sample have the same level of lightfastness on the plain paper, but that the reference sample has a lowerand decreased light fastness on the glossy paper than on the plain paperwhile the present invention sample has a higher and increased lightfastness.

The comparison in the results of the magenta dye alone with acombination of the magenta dye and the copper phthalocyanine type cyandye is as follows. In the reference samples (in comparison of No.2-1with No.2-2 to 2-4), the color differences in the combination case arealmost none or slightly exceed that of the magenta alone on the plainpaper, but they increasingly exceed on the glossy paper. On the otherhand, in the present invention samples (in comparison of No.1-1 withNo.1-2 to 1-4), the color differences in the combinations case are muchsmaller than that of the magenta alone on both the plain and glossypaper. These facts mean that, in a combination with metal phthalocyaninetype cyan dye, the reference sample has the same or decreased lightfastness while the present invention sample has an increased lightfastness.

Industrial Applicability

The anthrapyridone compound used in the present invention is excellentin solubility in water and is characterized as having a good ability tofilter through a filter material such as membrane filter. Theanthrapyridone compound is highly safe for a humane body. Furthermore,the ink composition of the present invention using the anthrapyridonecompound neither show a crystal deposition after a long storage nor achange in property (for example, an elapse change in viscosity orsurface tension) and a color. It has good storage stability. The inkcomposition of the present invention, when used as a magenta ink forink-jet recording, can give a printed matter excellent in light fastnessand water fastness. Furthermore, the ink composition, when used togetherwith a yellow, cyan or black dye, also enables ink-jet recordingexcellent in light fastness and water fastness. The ink compositiondisplays the effect strikingly when applied to an information paper,especially to the one having an ink-acceptable layer. The inkcomposition, when used together with a metal phthalocyanine type cyandye, can also increase a light fastness, and, additionally, provide aclear printed surface and an ideal magenta color. The ink composition,when used together with a yellow or cyan ink, can provide a wide visibleray range of color tone.

Therefore, the ink composition of the present invention is very usefulas a magenta ink for ink-jet recording.

What is claimed is:
 1. A water-based magenta ink composition, whichcomprises the disulfonic acid derivative of a compound represented byFormula (2):

or the salt or the salt thereof in an amount of 85% or more by arearatio according to HPLC and a monosulfonic acid compound of the compoundrepresented by Formula (2) in an amount of 10% or less by area ratioaccording to HPLC as the dye component.
 2. A water-based magenta inkcomposition according to claim 1, wherein said disulfonic acid compoundis a compound represented by Formula (1)

or a salt thereof.
 3. A water-based magenta ink composition according toclaim 1, wherein said composition contains water and an organic solvent.4. A water-based magenta ink composition according to claim 1, whereinan inorganic salt is present in said dye component in an amount of 1% orless.
 5. A water-based magenta ink composition according to claim 1,wherein said composition is for ink-jet recording.
 6. A method forink-jet recording, comprising jetting ink droplets in response torecording signals to record on a recording material, said ink dropletscomprising the water-based magenta ink composition according to claim 1.7. A method for ink-jet recording, comprising jetting ink droplets inresponse to recording signals to record on a recording material, saidink droplets comprising the water-based magenta ink compositionaccording to claim 1, and a water-based cyan ink containing awater-soluble metal phthalocyanine dye.
 8. A method for ink-jetrecording according to claim 7, wherein said recording material is apolyamide fiber material, which is thermally treated after jetting saidink composition.
 9. A method for ink- jet recording according to claim7, wherein said recording material is a sheet for informationtransmitting.
 10. A method for ink-jet recording according to claim 9,wherein said sheet for information transmitting is a surface-treatedsheet.
 11. An ink-jet printer equipped with a container storing thewater-based magenta ink composition according to claim 1 and a containerstoring a water-based cyan ink containing a water-soluble metalphthalocyanine dye.
 12. A dye for water-based magenta ink, whichcomprises a disulfonic acid compound represented by Formula (1)

or the salt thereof in an amount of 90% or more by area ratio accordingto HPLC, the monosulfonated product of the compound represented byFormula (2)

in an amount of 5% or less by area ratio according to HPLC, and theinorganic salt in an amount of 1% or less.
 13. A method for producing adye comprising the disulfonic acid compound represented by Formula (1)

or the salt thereof in an amount of 85% or more by area ratio accordingto HPLC and a monosulfonic acid compound of the compound represented byFormula 2

in an amount of 10% or less by area ratio according to HPLC, whichcomprises disulfonating the anthrapyridone compound represented byFormula (2) with fuming sulfuric acid, salting out conventionally thedisulfonic acid compound thus obtained to give a wet cake, and thentreating the wet cake with hydrous lower alcohol.
 14. A method forink-jet recording, comprising jetting ink droplets in response torecording signals to record on a recording material, said ink dropletscomprising the water-based magenta ink composition according to claim 4.15. A method for ink-jet recording, comprising jetting ink droplets inresponse to recording signals to record on a recording material, saidink droplets comprising the water-based magenta ink compositionaccording to claim 4, and a water-based cyan ink containing awater-soluble metal phthalocyanine dye.
 16. A method for ink-jetrecording according to claim 15, wherein said recording